Microincision versus small-incision coaxial cataract surgery using different power modes for hard nuclear cataract

PURPOSE: To compare the efficacy of microincision and small-incision coaxial phacoemulsification in treating hard cataracts using different ultrasound power modes. SETTING: Department of Ophthalmology, Seoul St. Mary's Hospital, College of Medicine, Catholic University of Korea, Seoul, Korea. DESIGN: Randomized clinical trial. METHODS: Eyes with hard cataract were randomized to have an initial incision of 1.80 mm, 2.20 mm, or 2.75 mm. The eyes in each group were equally randomized to treatment with burst, pulse, or continuous mode. Ultrasound time (UST), mean cumulative dissipated energy (CDE), corrected distance visual acuity (CDVA), surgically induced corneal astigmatism, incisional and central corneal thickness (CCT), and endothelial cell counts were evaluated. RESULTS: The study enrolled 180 eyes, 60 in each group. Two months postoperatively, there were no statistically significant differences in UST, CDE, CDVA, CCT, or percentage endothelial cell loss between the 3 incision groups. The 2.75 mm incision induced more astigmatism at 2 months and less incisional corneal edema at 1 week than the 1.80 mm or 2.20 mm incision (P<.05). The UST, CDE, incisional corneal thickness, and CCT at 1 week and the percentage endothelial cell loss at 2 months with continuous mode were statistically significantly higher than with pulse mode and burst mode in all 3 incision groups (P<.05). CONCLUSIONS: Phacoemulsification using microincisions may be as safe and effective as the conventional small incision for hard cataract. The intraoperative energy use and ocular damage was less with the pulse and burst modes than with the continuous mode.